Coating of articles



July 29, 1947; P, WHITE 4 2,424,949

comma 0F ARTICLES. 4

, Fi ledNov. 25, 1944 a l 'y a I mznlor Te icy 7771i 2e B Y iltorngyr Patented July 29, 1947 COATING F ARTICLES Percy White, Earlestown, Newton-le-Willows, England, assignor to T. & T. Vicars Limited, Earlcstown, Newton-le-Willows, England Application November 25, 1944, Serial No. 565,125 In Great Britain November 8, 1943 Section 1, Public Law 690, August 8, 1946.

Patent expires November 8, 1963 This invention relates to improvements in the coating of articles with plastic material, as in the application of a layer of cream or soft plastic material to biscuits.

An object of the invention is to enable a layer of soft plastic material of predetermined thickness and shape to be applied to a' rigid article such as a'biscuit without the application of friction or pressure to the articles, and irrespective of the shape or contour of the surface of the article to which said layer is to be applied.

According to this invention plastic material is passed into the cutaway spaces of a stencil of predetermined thickness and shape thus determining a measured shape and quantity of the said material which is then exuded from the 2 Claims. (Cl. 107-54) space in the stencil by means of air pressure so that the detached 'wad of plastic material may fall upg'n the surface of the article to be coated. It/will be seen that by this means the biscuit or the like article to be coated need not be in frictional or even rolling contact with the outer face'of the stencilso that biscuits which may have an irregular or a rough upper surface can.

be effectively coated.

It will be preferred that plastic material be forced right through the stencil openings, the

.excess of material on both sides of the stencil plate being removed by scrapers prior to the exuding 'of the wad of material within the cut-- cylinder and may be of any desired contour.

A supply of plastic material 3 is fed to the interior of the cylinder or drum I by means not shown, so that during the rotation of the drum I this plastic material is forced into and through the openings 2, being scraped from the outside surface of the drum or cylinder l by a cantilever scraper 4 preferably having an arrow-head 5, so

that the maximum pressure comes to bear on the stepped edge 6 of this head against the surface of the cylinder I. Means such as a set screw 1 may be provided to apply adjustable pressure to the doctor or scraper 4.

-on a link rotatable about the center of the This scraper is mounted on a pivot l5 which is preferably adjustable in position relatively to the hollow cylinder for instance by being carried hollow cylinder.

The material 3 is scraped from the inside of the cylindrical stencil 2 by means of an adjustable scraper blade 8 which may be formed as shown integral with an air pressure ejecting nozzle 9 connected to an airpressure supply pipe Ill. It will consequently be seen that as the stencil l rotates relatively to the fixed scraper blades 4' and 8, material 3 will be compressed into the stencil openings and will be left as a wad within these openings only, prior to ejection from the openings 2 by the air passing out through the nozzle 9 which nozzle may extend the-full internal width of the hollow cylinder or at least slightly wider than the openings 2 in this cylinder.

It will be appreciated that where a doctor or blade moves over an opening containing plastic material the efiect often is to roll up the plastic material so that this becomes compressed up against a back'edge of the opening but leaves the forward edge of the opening, and to avoid this I effect an abutment or hump 2b is mounted on the back of the stationary nozzle 9 and scraper blade 8 forming a compression pocket i l for the plastic material and preventing this from rolling back as it comes subject to the action of the scraper blade 8.

With most plastic materials it will be found that as soon as the front edge 12 of a wad of plastic material is ejected from the opening 2 in the stencil, the rest of the wad will automatically peel'away, so that it is not always essential to provide a constant air pressure either from a blower, connected to the pipe I feeding it giving a constant air pressure, or means maybe provided to periodically give an impulse of air pressure to the supply pipe l0, operating in synchroism with the rotation of the cylinder, such as an air valve operated by a cam driven from, and timedirom, the cylinder so that an air pressure wave is passed to the nozzle 9 just as the leading edge of a stencil opening comes into coincidence with it, that is to say, in the position shown in the drawing.

The invention is generally applicable where it is desired to provide a thin layer of plastic material of any predetermined shape and thickness in the form of a. wad to be'applied to articles, and is particularly applicable .for instance, by way of example, to the application of a wad or layer of cream, fruit pulp or other plastic material to biscuits in which the wad, as shown in the drawing, comes to lie upon biscuits such as l3 moving in spaced relationship onv a conveyor I4 which is moved forward in synchronism with the rotation of the stencil drum l.

It will be appreciated that'the wall of the stencil drum I will have a thickness substantially equivalent to the thickness of the wad or layer 3 it is desired to lay upon successive-articles such asbiscuits. v V g- It will ibe'preferred. to provide meansv for the conditioning of the air fed to the nozzle 9, that is to say in certain cases it may be desired to cool 4 from one side to the other to progressively eject the wad from the stencil while confining the progressively diminishing remaining part of the wad in the stencil. I

2. A'method of applying-a layer of plastic material to an article consisting informing a wad of material within'the confines of an opening in a, stencil plate by supplying material to'the stencil this below -atmospheric temperature or at other times to heat it above atmospheric temperature.

The present invention has beemdescri-bed with reference to a stencil in the'formpf ai'otating cylinder, but it will be obvious that'it is equally applicable to an arrangement in which'the stencil I h 15 form of a rotatable i may 'be in the form of a flat plate oscillating to and fro, or again in the or shallow cone.

In each case it will be preferred that the stencil is adjustable in position relatively to the articles on which the walls of plastic material are to be deposited.

Air fed to the pipe I ll from a'chamber 2| can be heated for instance by aisteam coil or electric resistance element 22; p v i I declare that what I claim is: 1. A method of applying alayer of plastic material to an article consisting in taking up plastic material within the confines of an opening in a stencil plate and then progressively applying fluid pressure .to the wad confined within saidi'opening i plate, then scraping it oil on both sides, and then applying fluid pressure to said wad on one side thereof. to eject the same from said stencil plate progressively subsequent to its formation in said operiing'by said scraping action.

, I PERCY WHITE.

CITED REFERENCES 

